Dynamic Response Analyses and Experimental Research into Deep-Sea Mining Systems Based on Flexible Risers

The deep seabed is known for its abundant reserves of various mineral resources. Notably, the Clarion Clipperton (C-C) mining area in the northeast Pacific Ocean, where China holds exploration rights, is particularly rich in deep-sea polymetallic nodules. These nodules, which are nodular and unevenly distributed in seafloor sediments, have significant industrial exploitation value. Over the decades, the deep-sea mining industry has increasingly adopted systems that combine rigid and flexible risers supported by large surface mining vessels. However, current systems face economic and structural stability challenges, hindering the development of deep-sea mining technology. This paper proposes a new structural design for a deep-sea mining system based on flexible risers, validated through numerical simulations and experimental research. The system composition, function and operational characteristics are comprehensively introduced. Detailed calculations determine the production capacity of the deep-sea mining system and the dimensions of the seabed mining subsystem. Finite element numerical simulations analyze the morphological changes of flexible risers and the stress conditions at key connection points under different ocean current incident angles. Experimental research verifies the feasibility of collaborative movement between two tethered underwater devices. The proposed deep-sea mining system, utilizing flexible risers, significantly advances the establishment of a commercial deep-sea mining system. The production calculations and parameter determinations provide essential references for the system's future detailed design. Furthermore, the finite element simulation model established in this paper provides a research basis, and the method established in this paper offers a foundation for subsequent research under more complex ocean conditions. The control strategy for the collaborative movement between two tethered underwater devices provides an effective solution for deep-sea mining control systems.